Whatever puts your seat where you want it to be.
Nicolai gives the seat tube angle as 73.2 degrees, with a 545mm fork (A to C). I think I would need some set back; others might manage with a straight post.

i'm with jerky. Thomson X4 50mm stem, lots of spacers underneath (about 15mm to begin with), then dial in height to suit.
however, i'd tend to size the bike right rather than buy a layback post. the AM benefits from a steeper than normal seat angle for climbing compared to other 160mm AM rides and as such adding a layback post will put too much weight over the rear wheel causing the steering to go wallowy on steep ascents. not recommended !
i saw your frame in gravity sports handbrake - bright white ! lets see the pics once built up.

With the AM you dont want too much weight over the back (As you'll get with a layback) as it'll make the front twitchy and effect handling, and the handling is so GOOD you dont want to spoil it! If you put an inline post you should be able to put your seat at the farthest setback position and deal from there, if you cant you should have bought a large!

nothing wrong with the moto brake....apart from the bent lever, and some seal or airlock issues .

Any way, despite the non matching brakes, I took it to Afan on Sunday. Effin' brilliant bike!!!!! I'm not the bravest rider, but it allowed me to ride off/down stuff that really phased me on the old CC(even with pikes fitted). Obviously it's a little more work up the hills, but that could be equally blamed on the rider not getting out enough! Very nimble on the alpine black section and energy trails. I need a bit more time to dial in the air pressures, but so far I'm REALLY pleased.

Gravity sport have been more than helpful, and quick to deal with the odd niggle which always crop up on this kind of build. I can't rate them highly enough......but you people already know that, don't you!!

glad you like it handbrake - truly an All Mountain capable machine. climb brilliantly, descend brilliantly, singletracks well, but still no flying machine in the tight stuff....Hummer and Ti456 fill that gap for me
There's not a lot of dial in required on the AM As the chassis is bob-free and stiff enough not to worry. simply set your sag at 30% front and rear to begin with, set your rebound so you're not propelled out the saddle, and it's good to go - really as easy as that as your 1st reference point.....
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